Topics
12. Geometry
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AustraliaNSW
Stage 3

12.01 2D shapes

Lesson
Practice
Lesson

Are you ready?

Being able to  name 2D shapes  can help us in this lesson.

Examples

Example 1

What is the name of the shape in the picture below?

The image shows a rectangle.
A
Triangle
B
Rectangle
Worked Solution
Create a strategy

Think of a shape that has 2 pairs of opposite sides with equal lengths.

Apply the idea

From the option above, the shape that has 2 pairs of opposite sides with an equal length is a rectangle.

So the correct option is B: Rectangle

Idea summary

To help work out the name of a shape, think about properties like:

  • How many sides it has

  • What sides are the same length

Shape names and properties

This video looks at the names of 2D shapes.

Loading video...

Examples

Example 2

How many edges does each shape have?

a
The image shows a square.
Worked Solution
Create a strategy

We can count the straight lines around the square.

Apply the idea

The square has 4 straight lines around it.

So it has 4 edges.

b
The image shows a kite.
Worked Solution
Create a strategy

We can count the straight lines around the kite.

Apply the idea

The kite has 4 straight lines around it.

So it has 4 edges.

Idea summary

To find the number of edges of a shape, count the number of lines that go around the shape.

Outcomes

MA3-15MG

manipulates, classifies and draws two-dimensional shapes, including equilateral, isosceles and scalene triangles, and describes their properties

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